I. Field of the Invention
This invention relates to medical pressure transducers and, more particularly, to such transducers in which a disposable fluid path component such as a dome is selectively attachable to a reusable sensor component with respective fluid pressure communicating diaphragms of the components in confronting, pressure communicating relationship.
II. Description of Prior Art
In hospital environments, for example, many procedures involve monitoring bodily fluid pressures such as blood pressure. Typically, such pressure is monitored with a medical pressure transducer outside the patient's body and coupled hydraulically to the patient's circulatory system, by way of example, via a catheter introduced into the body. The catheter is coupled via a tube to a fluid path inside the transducer and the tube is filled with saline to hydraulically communicate pressure within the patient's body to the transducer.
The transducer includes a sensor in pressure communication with the fluid path by which to convert the pressure therein to electrical signals corresponding to the pressure. The electrical signals are coupled via a cable to a monitor which provides a visual display of the pressure.
One particularly successful form of such a transducer is provided by a two-component system in which one component with the expensive sensor is reusable, and the other component with the patient-contacting fluid path is disposable. Each component is provided with a diaphragm closing off access to the sensor or the fluid path, respectively. To measure pressure in the fluid path, the disposable component is screwed onto the reusable component with the diaphragms in confronting, pressure communicating relationship to thereby communicate pressure from the fluid path to the sensor. After use, the disposable component is unscrewed from the reusable part and discarded, and replaced with a new, sterile unit.
U.S. Pat. No. 4,920,972, the disclosure of which is incorporated herein by reference, shows an example of a two-component transducer in which the disposable fluid path component, referred to as a fluid dome, is rotatably coupled to the reusable sensor portion. The components are secured together by threaded interaction to bring the diaphragms into confronting, pressure communication relationship by relative rotation between the dome and reusable component and the diaphragms thereof.
While there has been success with such screw-on types of transducers they can be difficult to manipulate and can present other impediments to their use. For example, the diaphragms tend to rub together over a significant part of the rotational travel of the dome and reusable component. This rubbing causes a wearing effect on the diaphragms, and especially the reusable diaphragm which must remain intact for multiple uses. The wearing of the reusable diaphragm is thus of particular concern as there can be a noticeable shortening in the useful life of the reusable component and its performance may be adversely affected as the wear becomes pronounced.